Epidemiology and Prevention of Congenital Heart Defects

Abstract

Congenital heart defects are common, costly, and critical - and they are more so than they ought to be because of the limitations of treatment and the inability to prevent what can be prevented. Major heart defects occur in nearly 1 in 100 births, or 1.2 million babies worldwide every year, and severe heart defects in 1 in 300 births, or approximately 340,000 worldwide. These account for 1 in 3 neonatal deaths and nearly 1 in 10 infant deaths in developed countries. Treatment is costly: heart defects are the most expensive birth defect, and medical costs are only a fraction of the true costs, which accumulate over a lifetime (many complex heart defects are treated, not cured) and affect also the productivity of patients and families. As survival has improved in the last decades, the number of adolescents and adults with heart defects has increased: estimates suggest that, at least in North America, currently more adults are living with heart defects than children, underscoring the need for appropriate services in this population. Potent genetic factors (mostly chromosomal anomalies but also genomic imbalances and rare Mendelian conditions) account for at least 15% (perhaps 30%) of cases. Subtler genetic effects, particularly in the context of gene-environment interactions, have been postulated but to date have not been well characterized. Maternal and environmental factors are also incompletely known, but a few are well characterized and prime targets for primary prevention. These include maternal chronic illnesses, especially diabetes, select medications, and probably smoking and obesity. Multivitamin supplementation is a likely protective factor, though, unlike for neural tube defects, folic acid alone in small amounts may not be. The key for primary prevention is to begin from before conception and target multiple risk factors in an integrated approach aiming at optimal health through the lifespan. This approach will not only reduce the risk for heart defects, but also promote the overall health of the fetus and the woman. Several competing forces and trends will likely modify the epidemiology and prevention of heart defects - prenatal diagnosis and terminations, newborn screening, changing rates of risk factors (e.g. the rise in diabetes in developing countries or new teratogens), etiologic research, approaches to treatment and care, and the increasing focus on preconception care. A concerted effort between researchers, clinicians, and public health professionals will be crucial in improving outcomes and fulfilling the promise of prevention.